1 pound large shrimp in shell (21 to 25 per lb), peeled, leaving tail and first segment of shell intact, and deveined

2 1 1/2- to 2-inch-long fresh Thai chiles or 1 serrano

Heat oil in a 1-quart heavy saucepan over moderate heat until hot but not smoking, then fry shallot, stirring, until golden brown, about 2 minutes. Transfer with a slotted spoon to paper towels to drain (shallots will crisp as they cool). Reserve oil. Soak tamarind pulp in boiling-hot water in a ...